/*
 * This is the source code of Telegram for Android v. 3.x.x
 * It is licensed under GNU GPL v. 2 or later.
 * You should have received a copy of the license in this archive (see LICENSE).
 *
 * Copyright Nikolai Kudashov, 2013-2017.
 */

package org.telegram.ui.Components;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.Application;
import android.os.Build;
import android.os.Bundle;
import org.telegram.messenger.BuildVars;
import org.telegram.messenger.FileLog;
import java.util.concurrent.CopyOnWriteArrayList;

@SuppressLint("NewApi")
public class ForegroundDetector implements Application.ActivityLifecycleCallbacks
{
    public interface Listener
    {
        void onBecameForeground();
        void onBecameBackground();
    }

    private int refs;
    private boolean wasInBackground = true;
    private long enterBackgroundTime = 0;
    private CopyOnWriteArrayList<Listener> listeners = new CopyOnWriteArrayList<>();
    private static ForegroundDetector Instance = null;

    public static ForegroundDetector getInstance()
    {
        return Instance;
    }

    public ForegroundDetector(Application application)
    {
        Instance = this;
        application.registerActivityLifecycleCallbacks(this);
    }

    public boolean isForeground()
    {
        return refs > 0;
    }

    public boolean isBackground()
    {
        return refs == 0;
    }

    public void addListener(Listener listener)
    {
        listeners.add(listener);
    }

    public void removeListener(Listener listener)
    {
        listeners.remove(listener);
    }

    @Override
    public void onActivityStarted(Activity activity)
    {
        if (++refs >= 1)
        {
            if (System.currentTimeMillis() - enterBackgroundTime < 200)
                wasInBackground = false;

            if (BuildVars.LOGS_ENABLED)
                FileLog.d("switch to foreground");

            for (Listener listener : listeners)
            {
                try
                {
                    listener.onBecameForeground();
                }
                catch (Exception e)
                {
                    FileLog.e(e);
                }
            }
        }
    }

    public boolean isWasInBackground(boolean reset)
    {
        if (reset && Build.VERSION.SDK_INT >= 21 && (System.currentTimeMillis() - enterBackgroundTime < 200))
            wasInBackground = false;

        return wasInBackground;
    }

    public void resetBackgroundVar()
    {
        wasInBackground = false;
    }

    @Override
    public void onActivityStopped(Activity activity)
    {
        if (--refs <= 0)
        {
            enterBackgroundTime = System.currentTimeMillis();
            wasInBackground = true;

            if (BuildVars.LOGS_ENABLED)
                FileLog.d("switch to background");

            for (Listener listener : listeners)
            {
                try
                {
                    listener.onBecameBackground();
                }
                catch (Exception e)
                {
                    FileLog.e(e);
                }
            }
        }
    }

    @Override
    public void onActivityCreated(Activity activity, Bundle savedInstanceState) {}

    @Override
    public void onActivityResumed(Activity activity) {}

    @Override
    public void onActivityPaused(Activity activity) {}

    @Override
    public void onActivitySaveInstanceState(Activity activity, Bundle outState) {}

    @Override
    public void onActivityDestroyed(Activity activity) {}
}
